1. Field of the Invention
The present invention relates to a periodic magnetic field generation device, and a linear motor and a rotary motor using the same.
2. Description of the Related Art
Conventionally, as periodic magnetic field generation device used for a linear motor or a rotary motor and having a field pole configured by permanent magnets of a Halbach magnet structure, as disclosed in Japanese Unexamined Patent Application Publican No. 2007-006545 published on Jan. 11, 2007, for example, there is proposed a periodic magnetic field generation device having a structure of a Halbach magnet array provided with main pole permanent magnets magnetized in a direction of a generated field and sub pole permanent magnets magnetized in a direction opposite to the magnetic pole of the main pole permanent magnets, and in which a part of each of the main pole permanent magnets on a side on which a magnetic field is generated is replaced with a soft magnetic member.
By replacing a part of each main pole permanent magnet on the side on which the magnetic field is generated with a soft magnetic member, a periodic magnetic field generation device having such a structure is capable of alleviating an influence of magnetic saturation in a magnetic circuit in comparison with a periodic magnetic field generation device that is configured only by a Halbach magnet array, thereby increasing the generated field.
However, a periodic magnetic field generation device having a field pole configured by conventional permanent magnets of a Halbach magnet structure poses a problem that, as saturation magnetic flux density of the soft magnetic member itself is limited and as the magnetic flux density in the magnetic circuit increases due to an improvement in properties of recent permanent magnets, the generated field of the periodic magnetic field generation device is limited due to the magnetic saturation in the magnetic circuit.
Further, a linear motor or a rotary motor using the periodic magnetic field generation device also poses a problem that it is not possible to increase a thrust force or a torque as the generated field of periodic magnetic field generation device cannot be increased.
Moreover, although a Halbach magnet array used in the periodic magnetic field generation device can cause the generated field to show a sinusoidal wave distribution due to its structure, further sinusoidalization of the generated field is limited, and there is still much to be improved in order to improve a thrust force and reduce a thrust ripple of the linear motor and such.
The present invention is conceived of in order to address the above problems, and the present invention aims to provide a periodic magnetic field generation device whose generated field is further increased and sinusoidalized by changing a shape of a soft magnetic member or shapes of main pole permanent magnets and sub pole permanent magnets in a periodic magnetic field generation device having a Halbach magnet array. The present invention also aims to provide a linear motor and a rotary motor using such a periodic magnetic field generation device.